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1α , 25-dihydroxyvitamin D3 Promotes Fusion of Mouse Alveolar Macrophages Both by a Direct Mechanism and by a Spleen Cell-Mediated Indirect Mechanism
Etsuko Abe, Chisato Miyaura, Hirofumi Tanaka, Yoshiko Shiina, Takeo Kuribayashi, Satoshi Suda, Yasuho Nishii, Hector F. DeLuca and Tatsuo Suda
Proceedings of the National Academy of Sciences of the United States of America
Vol. 80, No. 18, [Part 1: Biological Sciences] (Sep. 15, 1983), pp. 5583-5587
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/14383
Page Count: 5
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Extensive fusion was induced in mouse alveolar macrophages by treatment with conditioned media obtained from splecn cell cultures treated with 15 μ g of phytohemagglutinin or concanavalin A per ml or with 12 nM 1α , 25-dihydroxyvitamin D3 [1α , 25(OH)2D3]. The fusion rate was 80-90% on day 3. In addition, 1α , 25(OH)2D3 added directly to alveolar macrophages induced fusion of about 35% of the cells on day 3, whereas direct addition of phytohemagglutinin and concanavalin A did not enhance fusion at all. When conditioned media from spleen cell or T cell cultures treated with 12 nM 1α , 25(OH)2D3 were applied to a Sephadex G-100 column, a fusion factor (Mr 37,000-70,000) could be separated from 1α , 25(OH)2D3. 1α , 25(OH)2D3 induced fusion at 0.012-120 nM in a dose-dependent manner both by direct action and by spleen cell-mediated indirect action, but the fusion rate was always much greater in the latter than in the former at each concentration of the vitamin. Of the vitamin D3 derivatives tested, 1α , 25(OH)2D3 was the most potent, followed successively by 1α , 24R, 25-trihydroxyvitamin D3, 1α -hydroxyvitamin D3, 25-hydroxyvitamin D3 and 24R,25-dihydroxyvitamin D3. These results clearly indicate that 1α , 25(OH)2D3 induces fusion of mouse alveolar macrophages by both a direct and an indirect mechanism, the latter mediated by spleen cells, probably by T cells.
Proceedings of the National Academy of Sciences of the United States of America © 1983 National Academy of Sciences